Transformers are used to raise or lower an AC voltage using a mutual induction principle. In line with increases in power demand, industrialization, etc., the capacities and voltages of such transformers have become large and ultra-high. These large capacity and ultra-high voltage transformers are used in, for example, large-scale industrial facilities or transformation stations. If an accident takes place in a large-capacity transformer, the ripple effect is widespread, and thus there is a need to perform insulation diagnosis for preventing an accident in a transformer.
That is, in order to secure the reliability of a transformer and stably supply electric power, an abnormality symptom which may be a clue of an accident needs to be detected in real time in the operating state of a transformer. For this purpose, a partial discharge detection device for detecting the operating state of a transformer in real time is used.
A partial discharge is generated when an insulation abnormality occurs in a transformer. A partial discharge detection device is used to detect such a partial discharge. The partial discharge detection device is installed within a power device, such as a transformer or the like, in the state of maintaining a predetermined insulation distance, and detects a partial discharge signal.
The installation form of the partial discharge detection device varies depending on the installation position thereof. In the case of a transformer, the installation position of the partial discharge detection device is located in the upper portion of the transformer or within a drain valve in the lower portion of the transformer. In the case where the partial discharge detection device is installed in the upper portion of the transformer, the partial discharge detection device can stably detect a partial discharge signal while preventing the outflow of an insulating fluid in the state of being filled with the insulating fluid. Meanwhile, in the case where the partial discharge detection device is installed within the drain valve, there is no need to form a separate window in the transformer. It is also possible to install the partial discharge detection device at each of the positions where drain valves are present.
In FIGS. 1 and 2, a partial discharge detection device according to the conventional art is schematically illustrated. First, FIG. 1 shows a state in which a partial discharge detection device 12 has been installed in a maintenance window 11 provided in the upper portion of a transformer 10. The partial discharge detection device 12 includes a signal reception unit 13 installed in the maintenance window 11 of the transformer 10. An N-type connector 14 for transferring a detected signal to the outside is employed in the partial discharge detection device 12. The N-type connector 14 is connected to a coaxial cable 15 and transfers a signal. The coaxial cable 15 is connected to a signal processing device 15′ and transfers a signal to the signal processing device 15′.
Meanwhile, in FIG. 2, a state in which a detection device 12′ has been installed in a drain valve 16 present on one side of the lower portion of a transformer 10 is shown. In the detection device 12′, an antenna unit is installed inside or outside an insulator and detects a partial discharge signal. In this case, an N-type connector 14 for transferring a detected signal to the outside is also employed in the partial discharge detection device 12′. The N-type connector 14 is connected to a coaxial cable 15 and transfers a signal. The coaxial cable 15 is connected to a signal processing device 15′ and transfer a signal to the signal processing device 15′.
However, the conventional partial discharge detection devices 12 and 12′ described above attempt to improve detection characteristics only through the improvement of the shape of the antenna unit or the improvement of the attachment structure of the antenna unit. Accordingly, the conventional technologies have their limitations on detecting a partial discharge in a transformer. That is, a problem arises in that the partial discharge detection devices 12 and 12′ cannot detect a partial discharge signal occurring in a partitioned portion within the transformer no matter how high the performance of the partial discharge detection devices 12 and 12′ may be.